1. Field of the Invention
The invention relates to a memory apparatus and a reading method thereof and more particularly, to a resistive memory apparatus and a reading method thereof.
2. Description of Related Art
A nonvolatile memory is capable of saving stored data after the power is turned off and is thus an indispensable memory device for many electronic products to function properly. Currently, a resistive random access memory (RRAM) is a type of nonvolatile memory that is being actively developed in the industry, which has advantages of having a low voltage for write operation, spending a short time for writing and erasing, having a long memorizing time, performing non-destructive read operation, being capable of multi-state memory, having a simple structure and small required area. Consequently, RRAM has great potential in the applications in personal computers and electronic apparatuses in the future.
Generally, a resistive memory cell may change a width of a filament path according to a level and a polarity of an applied pulse voltage. Thereby, a resistance may be set as in a low-resistive state (LRS) or a high-resistive state (HRS) in a reversible and non-volatile manner, so as to represent storage data with different logic levels. For instance, when data of logic 1 is written, a RESET pulse may be applied to break the filament path, such that the high-resistive state is formed. When data of logic 0 is written, a SET pulse with an opposite polarity may be applied to reconstruct the filament path, such that the low-resistive state is formed. Thereby, during data reading, the data of logic 1 or of logic 0 may be read according to read currents generated in different resistive states.
However, the resistance of the low-resistive state usually tends toward being increased at a high temperature, while the resistance of the high-resistive state usually tends toward being reduced at the high temperature. Such situation that the resistances vary with the temperatures usually leads to difficulty in differentiating the low-resistive state from the high-resistive state.